1. Detailed Description of the Invention
The present invention relates to an information providing apparatus and method, an information receiving apparatus and method, and a transmission medium and more particularly to an information providing apparatus and method, an information receiving apparatus and method, and a transmission medium enabled to provide information more efficiently by forming EPG information out of individual information and common information on [TV] programs.
2. Description of Related Art
Recently, digital television broadcasting was started in Japan, too, and programs have come to be offered to the audience on 100 or more channels. Such an increase in the number of programs complicates the operation to select a desired program out of them. Also, as the number of channels increases, on top of an increase in the quantity of the information involved, a program schedule for not only one day but also for a week or so ahead becomes required by the audience for watching programs in a planned manner. For this reason, the data quantity of the program schedule becomes tremendously large, and it becomes difficult for paper media, mainly newspapers, to provide program schedules as before. Moreover, in case there is a change in the broadcast schedule of any program, it is difficult to change the program schedule on a paper medium.
In this connection, it is proposed that an EPG (Electronic Program Guide) to support program selection should be transmitted from the program provider""s side to the audience. As international standard on this EPG, the format of DVD_SI (Digital Video Broadcast Service Information) is prescribed.
If a program schedule is turned into data as EPG and offered to the audience, extraction of EPG data received by a receiving apparatus will enable the titles of programs, a program schedule, channel logos and the like to be indicated on the display, and the desired program to be quickly and correctly selected. Furthermore, any alteration in the broadcast time of a program can be easily coped with, and the viewer can correctly reserve the video recording of or watch the desired program.
FIG. 16 shows an example of a variety of tables constituting an EPG according to the prior art. An NIT (Network_Information_Table) states the overall configuration of the network and information necessary for reception, and one NIT exists for each network. In this NIT is stated an SDT (Service_Description_Table).
An SDT exists for each stream. For instance, if this EPG is to be transmitted via a satellite, an SDT is defined for each carrier wave (each transponder). In an SDT, information on the channel for transmission on the carrier wave is stated in pfEIT, gEIT and dEIT. In the pfEIT (present_following_Event_Information_Table) are stated the program currently broadcast on that channel and the next program. In the dEIT (detail-Event_Information_Table) is stated a document concerning an outline of the event (program), and in the gEIT (general-Event_Information_Table) is stated information other than the outline document concerning the program.
On the other hand, where NVOD (near video on demand) service is operated, a dummy channel (d-ch) is provided besides the channel on which program information is delivered (ch). In the dEIT and the gEIT of the dummy channel, the outline document and other information on the program broadcast by NVOD are respectively stated. On the other hand, in the dEIT and the gEIT of the channel on which the video information of NVOD is actually broadcast, the dEIT or the gEIT of the dummy channel is respectively stated and referred to.
Such an EPG providing method according to the prior art involved the following problems.
(1) The quantity of information becomes too vastly large to be fully transmitted.
In digital satellite broadcasting, the number of channels reaches 100 to 200, and the period of a program schedule is from 1 week to 2 weeks. For each program, a program outline of 200 to 400 full-width characters is stated. All these put together, the quantity of data to be transmitted as an EPG would be 10 Mbytes to 20 Mbytes. This quantity of data, if converted into the number of newspaper pages, would be from 140 to 200 pages. In satellite broadcasting, the capacity of one transponder is 34 Mbps and, if the data quantity of an EPG is 10 Mbytes (=80 Mbits), it would take about 3 seconds (=80 Mbits/30 Mbps) to send all these data.
Since an EPG essentially is information incidental to programs and to be transmitted by using part of what is mainly intended for the transmission of video information and audio information, it is difficult to use a whole transponder. Supposing 10% of a transponder is used for EPG transmission, it will take nearly 30 seconds to send all the EPG data of 80 Mbits.
(2) The access speed is slow.
If all EPG information is stored and made accessible on the side of the receiving apparatus, the viewer, when desiring to look at the program schedule, can immediately have it shown on the display. However, if this is to be done, a memory of a large capacity will have to be provided on the receiving apparatus side, resulting in not only an enlarged circuit scale but an increased cost. A receiving apparatus generally is a consumer item, and should desirably be as inexpensive as possible. Should a memory be mounted on it, the cost of the receiving apparatus would be doubled on that account alone.
Then, if EPG data are not stored in the receiving apparatus and extracted as appropriate from the transmission wave when required, no memory of a very large capacity will be needed. In this case, if the receiving apparatus is to be able to take in required information as soon as possible, it will be necessary for the transmitting side to transmit EPG information reiteratively at comparatively short intervals. However, since it is impossible to transmit a large quantity of data by using a limited frequency band, the transmission intervals will be inevitably extended. As a result, there was the problem that, when an attempt was made on the side of the receiving apparatus to take in EPG data, it would be impossible to receive the desired data quickly and the time taken to display the program schedule tended to be extended.
(3) It is troublesome to manage EPG information on the transmitting apparatus side.
In order to make the desired information more readily accessible by the receiving apparatus, on the transmitting side a program schedule for 1 day (24 hours) is divided by eight into 3-hour segments for each channel and delivered as such. Therefore, when a program schedule for 1 week is to be delivered, 56 (=8xc3x977) 3-hour program schedules will be needed, and the number of program schedules for 200 channels will reach 11200 (=56xc3x97200).
(4) The delivery efficiency of 3-hour program schedules is poor.
Whereas 56 3-hour program schedules will be needed per service (per channel) as stated above, waste will arise when these program schedules are transmitted in the format of MPEG2 transport stream. Thus, the capacity of 1 packet of MPEG2 transport stream is supposed to be 188 bytes. While the program schedule of 1 program can be stated in 70 bytes, if the number of programs to be broadcast in 3 hours is 1, a program schedule having a capacity of only 70 bytes is delivered in 188 bytes, resulting in the stuffing of the difference of 118 (=188xe2x88x9270) bytes with dummy data.
Or where the number of programs to be broadcast in 3 hours is 3, the quantity of data needed to state them is 210 (=70xc3x973) bytes. If they are packeted in units of 188 bytes each, one packet will be fully used, but the second packet will be utilized for only 22 bytes, resulting in the wasting of 166 (=188xe2x88x9222) bytes.
Further, where no program is to be broadcast in 3 hours, only dummy data will be transmitted. Because, even if there is no information to be transmitted, a packet should be transmitted to search for the access position of the receiving apparatus. As a result, data corresponding to 30% to 40% of the quantity of information actually transmitted become substantially wasted data.
(5) The beginning of the program schedule cannot be retrieved in a single attempt.
It is so disposed as to transmit the program scheduled in 3-hour segments. When, for instance, a program schedule of programs whose broadcasting will start on or after 3:00 is to be displayed, first the program schedule for the time range of 3:00 to 5:59 is searched. Here, since the program schedule for this time range covers hours from 3:00 on, programs to be broadcast between 3:00 and 3:59 need to be displayed in the program schedule. If no program beginning between 3:00 and 3:59 is stated in the program schedule for 3:00 to 5:59, some program may be stated in the program schedule for the time range of 0:00 to 2:59. So, the program schedule for this time range is searched. If no program can be retrieved by this search, the program broadcast in that time range may have a still earlier broadcast start time. Then, again, the program schedule for the immediately prior time range will be searched. Such searching operation will be executed repeatedly until the program is retrieved. As a result, a long time would be needed before it becomes possible to display the result of search.
Of if the broadcast for the day on a given channel starts at 4:00, there will be no program in the hours before that, but, as this fact cannot be stated, the absence of a program will remain unknown unless the program schedules back to the final program of the previous day are searched. This adds to the time taken to retrieve a program.
(6) Since the coverage of the program schedule is unknown, the handling convenience is deteriorated.
As the program schedule is transmitted in 3-hour segments for each channel, one cannot know how many days ahead from the present time are covered by the transmitted program schedule by looking at the program schedule for only one time segment. Then, to find this out, program schedules for further time segments ahead should be searched successively and, when no program can be retrieved eventually, it is determined that there is no further program schedule. As a result, when the viewer instructs displaying of a program schedule for a day some time ahead, he or she will be kept waiting for a long time eventually to find the displaying of a message to the effect that there is no program schedule for the day, and be given an extremely disagreeable impression.
The present invention addresses such a situation and makes possible more efficient transmission of EPG information.
According to an aspect of the invention, an information providing apparatus includes first generating means for generating first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information; second generating means for generating the second information including information on the TV program; and synthesizing means for synthesizing the first information and the second information as EPG information.
According to another aspect of the invention, an information providing method includes a first generating step to generate first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information; a generating step to generate the second information including information on the TV program; and a synthesizing step to synthesize the first and second information as EPG information.
According to a further aspect of the invention, a transmission medium for transmitting a computer program includes a first generating step to generate first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information; a second generating step to generate the second information including information on the TV program; and a synthesizing step to synthesize the first and second information as EPG information.
According to yet another aspect of the invention, an information receiving apparatus includes receiving means for receiving signals including EPG information generated by synthesizing first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information, and the second information including information on the TV program; extracting means for extracting the EPG information from the signals received by the receiving means; and control means for controlling the displaying of the EPG information extracted by the extracting means.
According to a still further aspect of the invention, an information receiving method includes a receiving step to receive signals including EPG information generated by synthesizing first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information, and the second information including information on the TV program; an extracting step to extract the EPG information from the signals received at the receiving step; and a control step to control the displaying of the EPG information extracted at the extracting step.
According to an additional aspect of the invention, a medium for transmitting a computer program that includes a receiving step to receive signals including EPG information generated by synthesizing first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information, and the second information including information on the TV program; an extracting step to extract the EPG information from the signals received at the receiving step; and a control step to control the displaying of the EPG information extracted at the extracting step.
According to still another aspect of the invention, an information providing system transmits EPG information, superimposed on video signals, from an information providing apparatus and receives the EPG information with an information receiving apparatus. The information providing apparatus includes first generating means for generating first information including the identification code of a television [TV] program, the broadcast start time of the TV program, and information on reference to second information; second generating means for generating the second information including information on the TV program; and synthesizing means for synthesizing the first and second information as EPG information. The information receiving apparatus includes receiving means for receiving signals including video signals and EPG information; extracting means for extracting the EPG information from the signals received by the receiving means; and control means for controlling the displaying of the EPG information extracted by the extracting means.
According to yet a further aspect of the invention, an information providing method transmits EPG information, superimposed on video signals, from an information providing apparatus and receives the EPG information with an information receiving apparatus. The information providing apparatus is provided with a first generating step to generate first information including the identification code of a TV program, the broadcast start time of the TV program, and information on reference to second information; a second generating step to generate the second information including information on the TV program; and a synthesizing step to synthesize the first and second information as EPG information. The information receiving apparatus is provided with: a receiving step to receive signals including video signals and EPG information; an extracting step to extract the EPG information from the signals received at the receiving step; and a control step to control the displaying of the EPG information extracted at the extracting step.
According to yet an additional aspect of the invention, a medium for transmitting computer programs for use in an information providing system transmits EPG information, superimposed on video signals, from an information providing apparatus and receives the EPG information with an information receiving apparatus. A computer program for the information providing apparatus is provided with a first generating step to generate first information including the identification code of a TV program, the broadcast start time of the TV program, and information on reference to second information; a second generating step to generate the second information including information on the TV program; and a synthesizing step to synthesize the first and second information as EPG information. A program for the information receiving apparatus is provided with a receiving step to receive signals including video signals and EPG information; an extracting step to extract the EPG information from the signals received at the receiving step; and a control step to control the displaying of the EPG information extracted at the extracting step.
In the above-described information providing apparatus, information providing method, and transmission medium, EPG information is synthesized from the first information including the identification code of a TV program, the broadcast start time of the TV program, and information on reference to second information; and the second information including information on the TV program.
In the above-described information receiving apparatus, information receiving method, and transmission medium, EPG information synthesized from the first information including the identification code of a TV program, the broadcast start time of the TV program, and information on reference to second information, the second information including information on the TV program is extracted from received signals; and its display is controlled.
In the above-described information providing system, information providing method, and transmission medium, EPG information is synthesized in the information providing apparatus from the first information including the identification code of a TV program, the broadcast start time of the TV program, and information on reference to second information; and the second information including information on the TV program. Further in the receiving apparatus, EPG information synthesized from the first information including the identification code of a TV program, the broadcast start time of the TV program, and information on reference to the second information, and the second information including information on the TV program is extracted from received signals; and its display is controlled.